1. Field of the Invention
This invention relates to a connector and, in particular, relates to a connector in which a conduction path in the form of a conductor thin film is provided on a surface of an elastic body and this elastic body passes through and is supported by a through hole provided in an insulating frame. This type of connector is used for establishing electrical connection between connection objects such as between a board and a board or between a board and a semiconductor chip.
2. Description of Related Art
Use has been made of a connector in which a conduction path in the form of a conductor thin film is provided on a columnar body in the form of an elastic body so as to extend from an upper surface of the columnar body through a side surface thereof to a lower surface thereof and this columnar body is supported by a frame. With this type of connector, connection objects are respectively disposed on the upper and lower sides of the columnar body and fixed relative to the columnar body while holding the columnar body therebetween. In this event, the columnar body is elastically deformed to generate a reaction force. Using this reaction force, contacts between terminals of the connection objects and the conduction path on the upper and lower surfaces of the columnar body are maintained, thereby providing a stable conducting path between the two connection objects.
These contacts between the connector and the connection objects respectively occur between the thin film on the upper and lower surfaces of the columnar body and the terminals on the connection object sides. Even if a surface of a mating-side terminal has unevenness or is slightly inclined, a thin film provided on, such as bonded to, a surface of an elastic body can flexibly follow the surface of the mating-side terminal to achieve good surface-to-surface contact therebetween. Consequently, it is possible to suppress the contact resistance.
This type of conventional connector often uses a thin film as a conduction path as described above and thus the calorific value tends to be high so that it is difficult to increase the current capacity. While it is easy to suppress the resistance of a conduction path using no thin film, it is difficult in this case to suppress the contact resistance between a connector and a connection object.
Herein, “current capacity” represents a maximum current that can be supplied to a connector or a contact of a connector. Generally, when a current flows through a contact, the Joule heat is generated. This heat is transferred to connection objects, such as a board and a semiconductor chip, connected to a connector and further transferred to cables connected to the connection objects, various insulator members, and so on and is finally dissipated to an external space. The temperature of the connector or the contact is determined based on the balance between the heat generation and the heat dissipation described above.
In a connector, what tends to be most affected by heat is an insulator member. Generally, the continuous use temperature is determined for an insulator member. The continuous use temperature is a standard for long-term material property evaluation (heat resistance) prescribed in the UL (Underwriters Laboratories Inc.) Standard. In order not to impair the function of a connector, it is required to use the connector at or below the continuous use temperature.
According to the Joule's law, the Joule heat is proportional to the square of the current and to the resistance. Therefore, when the continuous use temperature of an insulator material and the resistance of a conduction path in a connector are determined, the maximum current that can be supplied without impairing the function of the connector is inevitably determined. This maximum current is defined as the current capacity.
This type of connector is described in JP-A-2008-21637 (hereinafter referred to as “Patent Document 1”). As shown in FIG. 20, the connector described in Patent Document 1 comprises an elastomer sheet having through holes 101 each provided therein with a conduction path 102. By providing the conduction path 102 in the through hole 101, broad conduction surfaces are ensured on front and back surfaces of the elastomer sheet. However, since the conduction path 102 is entirely formed by a thin film, its cross-sectional area is small. Consequently, it is difficult to reduce the resistance of the conduction path 102 as a whole.
JP-A-2007-323833 (hereinafter referred to as “Patent Document 2”) describes a connector comprising, as shown in FIG. 21, a metal fitting 111 that holds an elastomer between its arm portions (see paragraph [0032] of Patent Document 2). In this case, the metal fitting 111 serves as a conduction path. As shown in FIG. 21, the metal fitting 111 is formed by bending a metal plate having a thickness large enough to maintain its shape alone. When such a metal fitting 111 is used, contact between itself and a terminal on the connection object side may be point-to-point contact or surface-to-surface contact with a relatively small contact area, but cannot be surface-to-surface contact with a certain large contact area. Further, it is difficult to ensure surface-to-surface contact regardless of unevenness or inclination of a surface of the terminal on the connection object side. Consequently, it is difficult to reduce the contact resistance when the metal fitting 111 is in contact with the terminal on the connection object side.
JP-A-2007-328996 (hereinafter referred to as “Patent Document 3”) describes a connector comprising, as shown in FIG. 22, an elastomer plate 122 formed with a Π-shaped slit 120 along the peripheral edge of a metal terminal disposing region and thus with a tongue portion 121, which serves as the metal terminal disposing region, on the inner side of the slit 120 and a Π-shaped metal terminal 123 having a main post portion and a pair of arm portions extending from both ends of the main post portion and holding the tongue portion 121 therebetween (see paragraph [0024] of Patent Document 3). In the manufacture of this connector, the metal terminal 123 is formed by bending a metal plate in advance and then is fitted over the tongue portion 121 or, alternatively, a metal plate is first inserted through the slit 120 and then is bent and formed into the metal terminal 123 (see paragraphs [0036] to [0038] of Patent Document 3). As is also clear from this, the metal terminal 123 is formed by bending the metal plate having a certain thickness like the metal fitting 111 described in Patent Document 2. Consequently, as Patent Document 2, it is difficult to ensure surface-to-surface contact and thus to reduce the contact resistance, which, however, can be satisfactorily achieved by a thin film.